Muscle revision Flashcards
1
Q
2 types of muscle fibres
A
- myocytes
- myofibres
2
Q
Sarcolemma
A
- muscle cell membrane
3
Q
Sarcoplasm
A
- muscle cell cytoplasm
4
Q
Sarcomere
A
- contractile muscle unit formed by myofiibrils
5
Q
Myofibril
A
- accumulation of contractile proteins
6
Q
What does the sarcoplasmic reticulum store?
A
- calcium
7
Q
What surrounds myofibres?
A
- sarcoplasmic reticulum
8
Q
How does a muscle contract?
A
- neural signal travels down axon and activates calcium entry terminal axon
- calcium interacts with snare proteins outside acetylcholine vesicles at terminal axon
- this causes release of acetylcholine
- sodium enters the myofibre
- depolarisation current reaches the sarcoplasmic reticulum through connecting tubules
- calcium release within the sarcoplasm
- calcium binds to troponin
- tropomyosin unleashes actin
- contraction begins
9
Q
Function of sodium in muscle contraction
A
- speeds up the depolarisation/transmission at the junction
10
Q
Muscle fuel
A
- phosphagen system
- glycogen
- fatty acids
- branch aa
- lactate
11
Q
Phosphagen system
A
- CK stores & myokinase system
12
Q
How long does phosphagen system last for?
A
- 10-20s
13
Q
Does the phosphagen system use oxygen?
A
- no
14
Q
Main energy source for muscle
A
- glycogen
15
Q
Use of fatty acids as fuel for muscles
A
- endurance (sustained exercise)
16
Q
Branch aa fuel source
A
- gluconeogenesis & tricarboxylic acid cycle
17
Q
Is branch aa effective?
A
- has to go through gluconeogenesis so consumes more energy to produce glucose
- not effective
18
Q
How does lactate provide a source of fuel?
A
- NAD production
- liver cori cycle
19
Q
Does production of lactate increase or decrease the pH of cells?
A
- decrease
20
Q
What fibre type is aerobic?
A
- type I
21
Q
What fibre types are aerobic?
A
- type IIa
- type IIx
22
Q
What fibre type has the fastest contraction time?
A
- type IIx
23
Q
What fibre type has the most resistance to fatigue?
A
- type I
24
Q
What type of exercise are type IIa fibres used for?
A
- long term anaerobic activity
25
What type of exercise are type IIx fibres used for?
- short term anaerobic activty
26
Which type of fibre has the shortest duration of action?
- type IIx
-- less than 5 mins
27
Which type of fibre has the longest duration of action?
- type I
- hourse
28
Which type of fibre has the most power produced?
- type IIx
29
Which type of fibre has the lowest power produced?
- type I
30
Which type of fibre demands the most mitochondrial activity?
- type I
31
Major source of fuel of type I fibres
- creatinine phosphate
- glycogen
32
Major source of fuel for type IIx fibres
- ATP
- creatinine phosphate
- glycogen
33
Examples of type I muscle fibres
- myocardium
- core muscles (posture)
- extensors e.g. triceps, neck
- abaxial muscles
- intercostal muscles
34
Fibre type that should be prioritised if you want to train for speed
- type II
35
Fibre type that should be prioritised if you want to train for endurance
- type I
36
What oxidation is important for sustained exercise?
- fatty acid
37
Fastest source of energy
- ATP-PCr system
38
What happens if muscles work too hard?
- ROS mitochondrial respiratory chain
- Acetyl-carnitines in fatty acid oxidation
- lactate in glycolysis
39
3 hardest working structures in the body
- heart (muscles)
- brain
- liver
40
What does increased ROS do?
- breaks down cell membrane
- impairs the function of the mitochondria
41
Acetyl-carnitines
- intermediate product of fatty acid oxidation
42
Mechanisms for counteracting oxidative stress
- vitamin E
- cysteine
- Q10
43
Role of vitamin E
- sarcolemma repair
44
Best marker for muscle disease
- CK
45
2 markers of muscle disease
- CK
- AST
46
How to differentiate between CK & AST in horses
- SDH
- GGT
47
SDH
= sorbitol dehydrogenase
48
What equid species is GGT commonly high in?
- donkeys
49
When does CK peak?
- 6h
50
When does AST peak?
- 24h
50
How long does it take for AST to come down?
- weeks
51
Why is CK not elevated in cardiac disease?
- lab tests only measure MSK CK
- so not detecting the isomer of cardiac CK
52
What marker of cardiac muscle damage do lab tests look for?
- cardiac troponin
53
Why is MSK troponin not tested for?
- no need
- CK a better marker
54
Is there an injury if persistent AST & CK are seen?
- yes
55
If there's persistent AST does that mean there's persistent injury?
- no
56
57
2 types of muscle injury
- extertional
- non-extertional
58
Can cardiac troponin be naturally increased after exercise?
- yes
59
Classic clinical presentation of a myopathy
- stiff pelvic limbs
- low head carriage
- sweaty
